Taxonomic Status of the Colubrid Snake Sibynophis Subpunctatus (Duméril, Bibron & Duméril, 1854)
Total Page:16
File Type:pdf, Size:1020Kb
Hamadryad Vol. 28, Nos. 1 & 2, pp. 90 – 94, 2004. Copyright 2004 Centre for Herpetology, Madras Crocodile Bank Trust. TAXONOMIC STATUS OF THE COLUBRID SNAKE SIBYNOPHIS SUBPUNCTATUS (DUMÉRIL, BIBRON & DUMÉRIL, 1854) Ashok Captain1, David J. Gower2, Patrick David3 and Aaron M. Bauer4 13/1 Boat Club Road, Pune 411 001, Maharashtra, India. 2Department of Zoology, The Natural History Museum, London SW7 5BD, UK. Email: [email protected] 3Museum National d’Histoire Naturelle, Département Evolution et Systématique, UMS 602 - Taxonomie-Collection - Reptiles & Amphibiens, Case Postale N° 30, 25 Rue Cuvier, F-75231 Paris Cedex 05, France. 4Department of Biology, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085, U.S.A. ABSTRACT.– There is confusion in the literature regarding the taxonomic status of the colubrid snake Sibynophis subpunctatus (Duméril, Bibron & Duméril, 1854). Originally described from the Western Ghats of India, occasionally S. subpunctatus has been considered a junior synonym of its north-eastern Indian congener S. sagittarius. Our preliminary re-examination of material, including type specimens, is consistent with the view that the two species are morphologically distinct. The two species appear to be geographically disjunct, with S. subpunctatus occuring in Sri Lanka and western peninsular India, and S. sagittarius in North and North East India. A more detailed reassessment is required. KEYWORDS.– Sibynophis, Colubridae, India, Sri Lanka, Western Ghats. INTRODUCTION including Smith (1943) and Taylor (1950) fol- The colubrid snake genus Sibynophis lowed this. Fitzinger, 1843 comprises some nine species In a revision of sibynophiines, Morgan (1973) (Appendix I) distributed in southern and considered Sibynophis subpunctatus a synonym south-eastern Asia. Up to three species are of Sibynophis sagittarius (Cantor, 1839), a spe- known from mainland India, S. collaris, S. cies originally described from Bengal, NE India. subpunctatus,andS. sagittarius (Das, 1994, Morgan (1973: 71) wrote, “Although Wall 1997), though the taxonomy of the latter two is (1907) suggested that Polyodontophis confused. Sibynophis subpunctatus (sensu subpunctatus (= S. subpunctatus), the name ap- Smith, 1943) was first referred to and figured plied to specimens from southern India and Cey- by Seba (1734: plate XI). Jerdon’s (1853: 528) lon, should be considered a synonym of P. mention of “Calamaria sagittaria”inpeninsu- sagittarius (= S. sagittarius), most workers have lar India probably also corresponds to S. continued to follow Boulenger’s arrangement subpunctatus (see Wall 1921: 84). Duméril et recognizing 2 species (e.g. Bourret, 1936; Tay- al. (1854) described Oligodon subpunctatum lor, 1950). In view of the clinal variation exhib- based on a single specimen from “Malabar” in ited in ventral numbers and dorsal coloration, I the Western Ghats region of peninsular India. feel that the recognition of only 1 species is war- Boulenger (1890) transferred the species to his ranted.” new genus Polyodontophis, and this was fol- Wall’s (1907: 824) proposed suppression of lowed by Wall (1907, 1921 and 1923), Prater S. subpunctatus was based on a single specimen (1924) and Fraser (1936-7). Schmidt (1926) with eight supralabials on the left side (with the may have first used the combination fourth and fifth contacting the eye) and nine Sibynophis subpunctatus, and later workers, supralabials on the right (with the fourth, fifth February, 2004] SYSTEMATIC STATUS OF SIBYNOPHIS SUBPUNCTATUS 91 and sixth contacting the eye). Boulenger (1890) the Museum National d’Histoire Naturelle, Paris had considered the number of supralabials to be a (MNHN) and The Natural History Museum, key character for distinguishing Polyodontophis London (NHM), respectively. Tooth counts for (now Sibynophis) subpunctatus from P. (= S.) seven specimens are presented in Table 1. Where sagittarius. After sending his specimen to Lon- observations overlap, our counts essentially don for examination, Wall (1907: 824) followed match those given by Wall (1923). Morgan Boulenger’s advice and united the two taxa. (1973: table 33) also presented data on the varia- However, Wall (1923: 599) later changed his tion in the number of maxillary teeth (32 to 48) in view: “Note.- In the Bombay Natural History 22 specimens matching his concept of S. sagit- Journal (Vol. XVII, p 823) I referred to a speci- tarius. The majority (18) of these specimens had men, that appeared to unite the characters of counts of 42 or greater, while two (32 and 35 subpunctatus and sagittarius, and which sug- maxillary teeth) match Wall’s counts for his con- gested the union of the two species under the lat- cept of S. sagittarius. Only two specimens (37 ter and older name. I am now in a position to and 39 maxillary teeth) fall between these values. show that the two species previously held as such Morgan did not explicitly link maxillary tooth are both valid, and that the specimen referred to counts with locality, but there is nothing to sug- is an aberrant subpunctatus. This view is based gest that the specimens with low tooth counts on skulls in my collection. The dentition is as fol- comprised anything other than the few available lows:- subpunctatus. Maxillary 44 to 45. Pala- northern Indian specimens, that can be putatively tine 23 to 24. Pterygoid 21. Mandibular 40. – identified as S. sagittarius. sagittarius. Maxillary 32. Palatine 14 to16. Morgan (1973) also considered variation in Pterygoid 13. Mandibular 30. The specimen re- putative S. subpunctatus and S. sagittarius in ferred to was probably from the Northern part of terms of scalation (numbers of supralabials, the Western Ghats as it was preserved in the infralabials, temporals, ventrals, and subcaudals) same bottle as a Lycodon flavomaculatus, which and coloration, and concluded that only a single has a very limited distribution. (q. v.)” Morgan species should be recognized. The majority (37 (1973) neither referred to Wall’s (1923) of 48) of the specimens examined by Morgan revalidation nor otherwise cited this publication. (1973: table 9) are from Sri Lanka and peninsular Wall’s (1907) earlier proposed synonymy India, and no substantial differences in mean and later (1923) revalidation may have caused ventral scale counts was detected between the some taxonomic instability. For example, Daniel samples from these two areas (contrary to De & Shull (1964: 740) noted that “There appears to Silva, 1969, who proposed Sri Lankan S. be confusion in collection records between this subpunctatus to comprise a distinct subspecies, species and S. sagittarius.” Morgan’s proposed S. s. ceylanicus). Thus, the supposed clinal varia- synonymy has received a varying reception, be- tion in S. sagittatius (sensu Morgan) is unevenly ing both ignored/rejected (though not explicitly distributed across its range, being absent across by e.g. Whitaker, 1978; P. De Silva, 1980; Sri Lanka and peninsular India, but present be- Deoras, 1981; Mahendra, 1984; Murthy, 1985, tween these areas and North/North East India. 1986, 1990; Welch, 1988; A. De Silva, 1990, Importantly, Morgan (1973: 66) noted that 1996, 1998; Das, 1994, 1996; Sharma, 1998, “Analysis of geographic variation in S. sagittar- 2002, 2003; Schleich & Kästle, 2002) and fol- ius is impeded by a low number of specimens lowed (e.g., implicitly by Murthy and Sharma, from the northern areas of the range.” 1978; Das, 1997; Vyas, 2000). Morgan (1973) discussed only maxillary tooth counts, but there are also substantial differ- REASSESSMENT ences in tooth counts for the palatal and mandib- We briefly reassessed Morgan’s proposed syn- ular elements between putative S. subpunctatus onymy by examining material of S. subpunctatus and S. sagittarius (Table 1). Sample sizes remain and S. sagittarius, including the types stored in small, but we consider these differences to be 92 HAMADRYAD [Vol. 28, Nos.1&2, substantial and taxonomically significant. Wall was an avid and insightful counter of teeth, and he considered the differences he observed be- nt missing or tween putative S. subpunctatus and S. sagittarius Mandible to be indicative of separate species. Smith (1943) listed some other differences in the external morphology of these two species, most notably the number of supralabials (seven Pterygoid or eight in S. sagittarius, nine or rarely eight in S. subpunctatus) and anterior temporals (usually one in S. sagittarius, two in S. subpunctatus - where the lower ‘anterior temporal’ is not in con- tact with a postocular). These differences hold Tooth Counts (left/right) true for the type specimens of S. sagitttarius and S. subpunctatus, which have seven and nine supralabials, and one and two anterior (and pos- terior) temporals, respectively, on each side (PD, . Counting was difficult for wet, whole specimens, so that DJG, pers. obs.). In conclusion, we do not find Morgan’s Maxilla Palatine Pterygoid Palatine + (1973) evidence to be sufficient basis for the sup- pression of Sibynophis subpunctatus, and thus S. sagittarius we recognise this species as valid pending a more and detailed reassessment. Sibynophis subpunctatus and S. sagittarius appear to be geographically disjunct, with the former species occurring in Sri d skull 46/44 24/23Lanka 21/21 and western 45/44 peninsular ?/40 India, and the lat- lls are part of Wall’s collection. Abbreviations: - = count not made; ? = eleme ter in central and northeastern India and neigh- bouring countries. Abdulali (1948) reported a aa dried skull dried skull 35/? ?/? 16/16 16/16 18/15 15/13 34/31 31/29 ?/? ?/30 specimen from Ambarnath, near Bombay Sibynophis subpunctatus (Mumbai) at the northern end of the Western Ghats of peninsular India as S. sagittarius. How- ever, examination (by AC and Varad Giri) of the only Ambarnath specimen of Sibynophis in the Bengal wet, whole specimen ~32/32 -/- -/- <30/27 29/>26 “Malabar”no data wet, whole specimen 42/>42? wet, whole specimen -/- 44/47collections -/- -/-of 44/42 the -/- Bombay 37/38 45/44 Natural 41/40 History Soci- ety (BNHS S.1312, deposited by Abdulali in 1956), found its supralabial and temporal scalation to agree with that of the holotype of S.